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[person] (July 1743 - 25 May 1805) British philosopher who sought to present a rational basis for the Christian faith. He is best remembered for his last book, Natural Theology; or, Evidences of the Existence and Attributes of the Deity, which was published in 1802. This work argues that God's design of the world is proven by the general happiness and well-being evident in the physical and social order of the world. He developed the now infamous "watchmaker analogy," in which he argues that just as one can infer the existence of a watchmaker from a watch, one can infer the existence of a creator from the existence of the world.

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[noun] The literal meaning is “seeds everywhere." A hypothesis that life on Earth began as seedlings that arrived through space from other worlds. First hypothesized by Anaxagoras (510–428 BCE), variations of panspermia have been revived in modern times.

[noun] An organism that lives on or in a host organism of another species. Parasites derive their food from and are detrimental to the host. Several examples of parasite-host relationships are: fleas living parasitically on mammals; mistletoe living parasitically on trees; the protozoan Plasmodium living parasitically in humans, for whom it causes malaria.

[noun] The concept that the simplest explanation that fits all of the data is the most likely (and therefore the best) explanation. In different disciplines, the most parsimonious explanation may require the fewest assumptions, the fewest number of steps in a process, or the fewest interacting components in a system. Related to Ockham's Razor.

[person] French mathematician, physicist, and philosopher born in Clermont, France (1623 - 1662 CE). Pascal made contributions toward the development of mechanical calculators and the study of fluids and pressure. His writings contributed to the development of the scientific method; and along with Pierre de Fermat he laid the foundations of probability theory which led to development of statistical methods. For further information see our module Statistics in Scientific Research.

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A French chemist and biologist, born in Dole, France (1822-1895). Pasteur founded the science of microbiology and proved that microorganisms cause most infectious diseases. He also invented the process of pasteurization, made significant contributions to the science of brewing and winemaking, and developed vaccines for rabies and anthrax.

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[noun] Principle developed by Wolfgang Pauli (1925) that states that no two electrons in an atom can have the same set of four, quantum numbers. This implies that a maximum of two electrons can reside at any given quantum level only if they possess opposite values for spin.

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[person] (February 28, 1901 - August 19, 1994) An American chemist, peace activist, author, and educator. Pauling was a pioneer in the fields of quantum chemistry and molecular biology, and is considered one of the most important scientists of the 20th century. He is a Nobel laureate in both Chemistry and Peace. One of Pauling's most important contributions to molecular biology was his work in 1949 showing that sickle cell anemia is caused by an abnormal protein. Pauling is also remembered, with both praise and criticsm, for his later work with vitamin C as a disease cure and preventative. He founded the Linus Pauling Institute of Science and Medicine, now part of Oregon State University, which researched micronutrients, phytochemicals, and other aspects of diet in controlling and preventing disease.

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[person] English statistician and geneticist born in London, England (1857-1936). Pearson is credited with establishing the field of mathematical statistics. His landmark book Grammar of Science discussed the importance that probability and correlation have in scientific research, and had a profound impact on many scientists including Albert Einstein. He refined the statistical concept of correlation and introduced the concepts of regression and the chi-square test.

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[noun] The process of subjecting scholarly work, research or ideas to the scrutiny of others who are experts in the same field (aka, peers). For further information see our module Peer Review in Scientific Publishing.

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A symbol representing a measure of the effective concentration of hydrogen ions in a solution, pH = -log [H+]. pH is a measure of the acidity (or basicity) of a solution, where values of 0 to 14 are possible. Acid solutions have a pH < 7, basic solutions have pH > 7, neutral solutions have pH = 7.

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[noun] A lipid or glyceride that contains a phosphate group. The phosphate group imparts a polar side to the molecule, while the lipid end remains relatively non-polar. Phospholipids are the main form of lipid in cell membranes.

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[noun] The evolutionary history of a group of organisms, or the sequence of events in the evolutionary development of a group of organisms. Phylogeny can also indicate the diagram or depiction of that history, sometimes called an evolutionary tree.

[noun] A physical constant used in quantum mechanics that relates the energy and frequency of particles, and also the wavelength and the momentum of particles. Given the symbol h, it was developed in 1900 by German physicist Max Planck.

[person] Theoretical physicist, born in Kiel, Germany (1858–1947), who won the Nobel Prize in Physics in 1918 for his research on quantum theory. Through his study of thermodynamics, Planck devised the theory that energy did not flow continuously, but was radiated in packets called quanta. Albert Einstein applied Planck's quantum theory to the photoelectric effect, while Niels Bohr applied the theory to the atom.

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[noun] The semi-permeable layer of tissue enclosing the cytoplasm of a cell. The plasma membrane separates and protects the cell's interior from the exterior environment and controls what passes into and out of the cell.

[noun] A covalent bond in which electrons are unequally shared between bonding atoms. A polar covalent bond is formed when one atom participating has a stronger affinity for electrons, or electronegativity, than its bonding partner. A polar bond will result in an equal distribution of electron charge across the bonding pair. Compare to polar covalent molecule.

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[noun] A molecule that has an unequal distribution of bonding electrons, which results in an asymmetrical electrical charge (or dipole) across the molecule. Polar molecules are formed when polar covalent bonds are oriented so that the molecule contains a partially charged positive end and negative end. As a result of the uneven electrical charge, polar molecules are commonly attracted to each other by dipole-dipole interactions. Polar molecules often dissociate in water to form electrolytes. Compare to ionic compound.

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[noun] The directionality of a magnetic field, which consists of a north and south pole of equal and opposite strength. Lines of magnetic force emanate from the north pole and terminate at the south pole. When the earth's magnetic north pole corresponds with the geographic north pole (as it does now), the polarity of the magnetic field is normal; when the magnetic north pole corresponds with the geographic south pole, the polarity of the field is reversed.

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[verb] To fertilize (in plants). Plants may be self-pollinating, or may need a pollinator to transfer pollen to the stigma, thus fertilizing the plant. Pollinators include insects, birds, small mammals, and the wind. The type of pollinator needed by a given plant is often very specific.

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[noun] One of a number of crystal structures a compound can form. Polymorphic compounds include silica, which can form various types of quartz, and calcium carbonate, which can form two minerals, calcite and aragonite. Not all compounds are polymorphic.

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[noun] In biology, the population is all individuals of a certain kind of plant or animal that live in a particular habitat. In statistics, a population is the complete set of possible observations that can be made. For example, if a scientist is studying the beak sizes of finches in the Galapagos Islands, the population is the beak sizes of all of the finches in the Galapagos. If a scientist is studying the age distribution in Brazil, then the population is the set of ages of all the people living in Brazil. Contrast with subsample.

[noun] In science, a positive control refers to a system that is exposed to a treatment with a known effect. Thus, the positive control helps to establish that a response will occur, or provides a measure of the response of a variable to a known treatment. For more information, see our module Experimentation in Scientific Research.

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[noun] The energy an object possesses by virtue of its position in relation to a field of force. For example, lifting a mass m by h meters increases its potential energy by m·g·h, where g is the acceleration due to gravity.

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[noun] In science, precision refers to the degree of specified detail which can be expressed in a value. For example, a value expressed to three decimal places can be considered more precise than one made to two places. The determination of precision is a function of the degree to which individual measurements vary around a central value. Values with high precision are highly reproducible because repeated measurement will reliably give a similar result; however, they may or may not be accurate. Precision relates to the statistical error associated with a value. Compare to accuracy. See the module Uncertainty, Error, and Confidence.

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[person] English chemist, natural philosopher and theologian, born in Yorkshire (1733-1804). He is most frequently noted for discovering oxygen. Priestly also isolated and characterized 7 additional gases, and his work furthered the scientific understanding of photosynthesis and respiration.

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[noun] The process of forming new organic material from carbon dioxide, generally through photosynthesis; the process by which plants take in carbon dioxide, water, and light to form sugar and release oxygen.

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[noun] In the sciences, a principle is a fundamental, primary, or general law or truth. For instance, one of the most basic principles in physics is the causality principle, which states that everything that happens has a direct cause.

[noun] The likelihood that a given event will occur. In statistics, probability is often expressed as a ratio of the number of actual occurrences of an event to the number of possible occurrences of the same event, i.e. there is a 50% probability of obtaining heads in a coin toss.

[noun] In science, prospective research refers to the study of events moving forward in time. Generally this is done by designing a scientific study, and tracking, observing, or evaluating the course of events within that study as they occur. For more information, see our module Comparison in Scientific Methods.

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[noun] Macromolecules that are polymers of individual amino acids arranged in a chain and joined together by peptide bonds (and so also referred to as polypeptides). A minimum polymer length of approximately 40 amino acid units appears to be a functional size limit, and polymers shorter than this limit are commonly referred to as peptides. Proteins comprise approximately 50% of the dry weight of cells and fill a number of purposes, both functional and structural.

[person] French chemist, born in Angers (1754-1826). Proust proposed that the proportions of substances that combine in a given reaction are always the same. This is now known as the Law of Definite Proportions or Proust's Law.

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[person] Greek mathematician and philosopher, born in Samos (ca. 569-475 BCE). Pythagoras is best known for his proof of the Pythagorean theorem, which states that the square of the hypotenuse of a right-triangle (c) is equal to the sum of the squares of the other two sides (a and b) such that a2 + b2 = c2. He also founded a movement called Pythagoreanism, which held everything could be both predicted and explained by mathematics.